The goal of this proposed project is to gain quantitative information regarding the therapeutic potential of combining common anti-tumor agents including x-ray and neutron radiation, with chemotherapeutic agents. The mouse hair follicle represents an in vivo model which can be induced to poliferate by plucking, producing a rapidly proliferating tissue. The follicle in the non-proliferating phase represents a tissue which is non-cycling yet can be evaluated for its ability to respond to drugs and radiation and repair of such injury. Radiation and drug effects are quantitatively measured by the degree of temporary alopecia produced in the proliferating and non-proliferating state. Timing and sequencing of various agents for an optimum response after radiation both in the proliferating and non-proliferating tissue will be examined with x-rays and with neutrons in multifractionated therapy regimens, where we anticipate that the therapeutic ratio might be maximized and where the normal tissue injury can be minimized. The ultimate goals of this effort should aid in planning rational radiation treatment of cancer in man.